33-Inch Tires in Metric: The Real Equivalents
A "33-inch tire" is any tire with roughly a 33-inch overall diameter. On a 20-inch rim, the metric equivalents of 33X12.50R20 are 325/50R20 and 305/55R20; on a 16-inch rim, the classic "metric 33" is 285/75R16. The right equivalent depends on your rim size.
Two languages, one tire
Off-road (flotation) sizes read in inches: 33X12.50R20 = 33" tall, 12.5" wide, 20" rim. Metric sizes encode the same tire differently: width in millimeters, sidewall as a percentage. Neither is more correct — but crossing between them trips everyone up.
The classic crossovers
| Inch size | Rim | Closest metric |
|---|---|---|
| 33X12.50R20 | 20" | 325/50R20 · 305/55R20 |
| 33X11.50R16 (≈) | 16" | 285/75R16 (the classic "33") |
| 35X12.50R20 | 20" | 325/60R20 |
| 37X13.50R24 | 24" | — usually inch-only territory |
"Closest" never means identical — the two systems use different step sizes, so expect a fraction of an inch difference in diameter or width.
Convert yours
The metric ↔ inch converter takes any size and ranks the standard equivalents on your rim by how close the diameter lands. Then sanity-check the swap against the ±3% rule in the size comparison calculator — and if you went bigger, see whether you need a re-gear.